capacity

But it was the Sierra Club, influenced by its first executive director, David Brower, that emerged as a leading proponent of the notion that the earth had a carrying capacity — that there was an optimum number for the planet’s population to be held at.

The population, then at around 211 million, continued to expand, and many who at first worried for the carrying capacity of the planet became preoccupied with walling off the country and keeping the global population at bay.

Having lost the backing of the Sierra Club, America’s anti-immigration movement turned more explicitly to climate change — and to one of Zuckerman’s Sierra Club colleagues, Leon Kolankiewicz, an environmental planner versed in sprawl and impact studies and a longtime proponent of the idea that the planet had a limited carrying capacity.

The UK prison population has roughly doubled in the last 30 years, with capacity lagging behind, and in September the system came within 100 places of running out of space altogether.

"What we have to be is more strategic - we have to make sure that prison capacity meets demand and that means we have to look at the question of demand on prison places and that's I think where looking at the sentencing regime is necessary and important."